Method of treating crankshafts



July 15, 1941. w. L. GROENE METHOD OF TREATING CRANKSHAFTS Filed Jan. 2,1940 6 Sheets-Sheet l Hal Hrl

in Hill "HI l-H July 15, 1941. w, L. .GROENE 2,249,242

METHOD OF TREAT ING CRANKSHAFTS Filed Jan. 2, 1940 6 Sheets-Sheet 2 July15, 1941. w. L. GROENE METHOD OF TREATING CRANKSHAFTS Filed Jan. 2, 19406 Sheets-Sheet 3 July 15, 1941. w. L. GROENE METHOD OF TREATING CRANKSHAFTS Filed Jan. 2, 1940 6 Sheets-Sheet 5 SUE July 15, 1941. w. GROENEMETHOD OF TREATING CRANKSHAFTS Filed Jan. 2, 1940 6 Sheets-Sheet 6Patented July 15, 1941 UNITED STA E METHOD or 'TREATINGCRANKSHAFTSWillard L. Groene, Cincinnati, Ohio, assignor to The R. K. Le BlondMachine Tool Company, Cincinnati, Ohio, a corporation of DelawareApplication January 2, 1940', Serial No. 312,065

(chast 1) V 7 Claims.

This invention pertains to a method of pro-- cedure in preparing therough forgings or castings and machining the bearing portions ofmulti-throw internal combustion engine crankshafts, particularly of thetype utilized in the automotive industry. The chief object of thisinvention is to provide a series of unique carefully coordinated stepsfor turning all of the line bearings and all of the pin bearings of suchcrankshafts with an extremely high degree of accuracy commensurate withthat of rough grinding operations heretofore done on; such crankshafts.It is one of the chief objects of this invention to provide a system ofsteps through which the crankshaft is passed and by which the variousbearing portions of the crankshaft are turned with runout of .001" orless.

Heretofore great difficulty has been experienced in former processes ofturning the various bearing portions of crankshafts and which formersteps have produced inaccurate work so that excessive final grinding hadto be undertaken to correct the difiiculty. As is well known in the art,excessive grinding operations are highly expensive and very wasting ofproductive time and it is therefore the object of this invention toadvance the turning art to a point not heretofore attained in such typeof work and to thereby eliminate the previously required expensivegrinding operations. e

In the past, processes of accurately turning crankshafts have beendefective because:

(a) The gripping of rough work surfaces for the turning of the linebearings of the crankshaft has been found impractical because of thedifiiculty of making a proper equalizing chucking device to grip theshaft and chuck it accurately on the axis of rotation of the'lathe.

(b) The roughwork gripping chucking device has failed because of theimpossibility of gripping the rough, scale covered web surfaces whichcaused the crankshaft to slip during the turning of the various bearingportions of the shaft, it being remembered that the slightest movementof the crankshaft in such chucking devices will render the importantresults of highly accurate turning within .001" or less whollyimpossible.

(c) When chucking devices utilizing machined locating notches on thewebs of the shaft are utilized, the difficulty has arisen from themachining of these locating notches n the webs which could not beaccurately done because the crankshaft would spring under such machiningoperations. this being awell known majorproblem in the high productivework of premachining locating areas on crankshaft webs.

It is therefore an object of the present invention to first provide asystem of machined locating holes in the sides of the webs ofthe'crankshaft which holesmay be machined therein without in any waydistorting the crankshaft hem its true axial position, that is, theshaft willbe bent in no way whatever'during machining of the prelocatingareas in the sides ofthe web because all forces set up in the crankshaftduring such, operations take place along the ,length of the crankshaft,not sidewise of the crankshaft as-in former methods.

..; 1 It is also an object to provide chucking mechanism, cooperatingwith such type of locating holes machined in the sides of the webs, inwhich the-clamping action of said chucking devices cooperating with saidlocating holes will'have no effect whatever on the axial displacement orbending of the crankshaft when placed in a lathe for the machining ofits various bearing portions. V

- Another object-of this invention is to set forth a series of uniquesteps to be followed beginning with the rough forging or casting of. thecrankshaft to the complete machining of all of the line bearings and allof the pin bearings of the crankshaft to extremely fine requirements ofaccuracy to thereby reduce tothe very minimum the subsequent finishgrinding and polishing operations required on the shaft and to therebygreatly reduce the time and cost of producin such crankshafts.

- Further features and advantages of this invenvticn will appear fromthe detailed description of the drawings in which:

Fig-I shows a rough forging or casting of a vmulti-throw crankshaft asit is received from the forge shop or foundry preparatory to thebeginning of machining operations.

Fig. II shows the first step in the process comprising drilling centerholes in the flange and stub ends of the crankshaft.

Fig. III shows the unique step of premachining locating holes in thesides of the webs of the crankshaft for purposes of chucking andlocating the crankshaft for subsequent turning operations on the linebearings and the pin bearings of the crankshaft. Y

Fig. IV is an end view of the crankshaft showing the position of thelocating holes in the sides of the webs as machined in Fig. III.

Fig V shows the method of applying the unique chucking mechanism to thepremachined locating holes in the sides of" the webs of the crankshaftfor supporting and rotating it in a double center drive crankshaft lathefor simultaneously machining all of the line bearing portions of thecrankshaft. T c

Fig. VI shows the setup'utilized" for simultaneously machining all ofthe pinbearings of the crankshaft after the completion of the linebearing turning, utilizing the machined'locating holes in the sides ofthe webs for the indexthe crankshaft for the :eration' and chuckingrequired therefore) 29 to ing and driving of the crankshaft for the pinturning operation.

Fig. VII is a view, on the line VII-VII of Fig. VI, showing one of thepot chucks for gripping the crankshaft in the pin turning operation.

Fig. VIII is a view, on the line VIII--VIII of Fig. VI, showing theother pot chuck for gripping the crankshaft in the pin turningoperation.

Noting Fig. I, the rough crankshaft forging or casting C, in thisparticular illustrative showing, comprises the line bearings I, 2, and3, the flange end 4, and the stub end 5, constituting the line bearingportions of the crankshaft. In this particular crankshaft there are fourcrank pins 6, I, 8 and 9, which are interconnected with each otherxandwith the line bearings I, 2 and 3 of the crankshaft by means ofappropriate webs III, II, I2, I3, I 4, and I5. The object of thisparticular methodical procedure of this case is to provide a series ofunique steps carefully coordinated so as to provide for the accurateturning of the line bearing portions of the crankshaft within thelimitof .001" or less runout and to likewise provide for the accurate turningof the pin bearings 6, I, 8, and 9 with commensurate high degree ofaccuracy.

Having the forging or casting as shown in Fig. I, the first step of theprocess is to drill the center holes I6 and I1 (Fig. II) in the ends ofthe crankshaft by means'of appropriate center drills I8, in the usualmanner customary in procedures with respect to machining these ends ofthe crankshaft. The center holes I6 and I1 thus prepared define-the,axis of rotation I9 of the crankshaft in relation to which the variousbearing portions are to be turned and accurately located at thecompletion of the machining operations.

Thegnext step then is to take the crankshaft, as shown in Fig. III,andmount the crankshaft Withits center holes I 6 and I! on appropriatecenters '29 and 2I carried in the frame 22 of a 'locatinghole drillingmachine of unique construction and design. This machine is provided witha series of drill spindles 23, 24, 25, 2'6, 21, and 28 which are axiallyreciprocatable and rotatable by appropriate means, as iscustomary indrilling machines, in theframe 22 of the machine. These spindles 23to28, inclusive, carry appropriate drills 29, 39, 3|, 32, 33, and '34respectively which are thereby axially reciprocate.-

ble and rotatable by the'work spindles through suitable chucks'35 or thework spindles.

After the crankshaft is placed on the centers 20 and 2I the variousdrills, (for illustrative purposes center drills are shown as beingpreferably used but this is not a limiting factor in the operation ofthis method, it being fully practicable to use any other'type of drillwhich will M make a suitable locating hole or impression in g1,

subsequent turning op- 34, inclusive, are appropriately fed parallelwith the axis of-rotation I9 of the crankshaft C to "drilllocating holesin the sides of the webs of the'crankshaft in such away that thepressure exerted by this machining or drilling opera- .tion'in no-waytends'to'bend or to spring the crankshaft from itstrue axial positioncifically, drill 29 machines the side of the web I5 which is utilized inthe pin turning operation. Drills 3i! and 3| respectivelydrilllocatingholes 3'1 and '38 in the side I9. Speof the web II while thedrills 33 and 34 out the respective locating holes '39 and'40 in the WI4. Drill 32 machines the locating hole M in the side of the web II) forthe pin turning operation. The holes in the webs II and I4 are utilizedin turning the line bearings of the crankshaft.

Thus these locating holes are machined in the sides of the webs of thecrankshaft by feeding movement and pressure on the crankshaft in adirection parallel to the axis of rotation I 9 of the crankshaft vsothatno axial displacement or bending of the crankshaft can take place. Thecrankshaft is now premachined ready for the turning operations on thevarious bearing portions of the crankshaft.

Referring now to Fig. V, in which is shown the crankshaft chucked in theunique set of chucking devices which engage the webs II and I4 by meansof the locating holes 31 and 38, in the web II and the locating holes-39and 40 in the web I4 with gripping jaws 42 and 43 of the chuckingdevices in the ring gears 44 of a double center drive line bearingcrankshaft lathe. These unique chucking jaws are pivotally mountedagainst lengthwise movement on pins 45 fixed in the ring gears 44. Theirserrated end portions 42a and the locating pins 46 engaged in thelocating holes 31, 38, 39, and 40 formed in the webs have clampingmovement in a direction parallel with the axis of rotation I9 of thecrankshaft so that the clamping action as effected by the clamping screw41 threaded in the jaw-43 and'passing through the jaw 42 has no effectwhatever in axially bending or distorting the crankshaft from its trueaxis I9 as these jaws 42 and 43 are bound up on the crankshaft webs IIand I4. The crankshaft is thus chucked for the operation of the cuttingtools T to machine all of the line bearing portions on the crankshaft.

The utilization of these machined locating holes'in the sides of thewebs, which can be machined in the setup shown in Fig. III without inany way distorting the crankshaft from Its true axial position I9,provides locating surfaces which are extremely accuratewith respect tothis axis of the crankshaft. By providing, in the chucking mechanismcooperating with these 10- eating holes in the sides of the web, aclamping "arrangement which is effective only in a line parallel withthe axis of rotation I9 of the crankshaft,'there can be no distortion inthe shaft due to the clamping action of the chuck on the work piece. Bythis arrangement of premachin- 'ing the locating holes in the sides ofthe web and of providing a chucking device whose clamping turned.

Having in this manner completed the highly accurate turning of the linebearing portions of the crankshaft, the crankshaft is then ready for theturning of the pin bearings 6, I, 8 and 9.

Referring to Fig. VI, the crankshaft C is here shown chucked in potchucks'48 and 49 of an 'orbital"lathe of a type, for example, as shownin Patent 2,138,964, having a steady rest 59 with a'locating hole 38 in7 -;I1xeg I the chuck bodies 48 and 49 concentric line bearings l and 3upon these half bushings 52 so as to properly align the axis of rotationof the crankshaft l9 and that of the lathe on the line I9. Appropriateclamping means, comprising the arcuate clamping jaws 53 actuated bysuitable cam bar 5t hold the line bearings l and 3 securely against thehalf bushing 52 in a manner fully disclosed in Patent 2,030,142 citedabove. The crankshaft is thereby accurately centered and aligned on theaxis of rotation IS in the lathe, the problem then being to index thecrankshaft accurately in the chucking devices 48 and 49 so as tobringthe respective pins 6, 1, 8 and 9 in proper synchronous rotativeposition with the orbital lathe tool mechanism and to provide mechanismfor driving and rotating the crankshaft with the chucks 48 and 49.

This mechanism comprises a plunger 55 which is axially slidable in eachof the chucking devices 48 and 49 parallel with the axis l9 of thelathe, and is adapted to be moved outwardly to engage the respectivelocating holes (35 and 4| formed in the respective webs l5 and H! of thecrankshaft thereby indexing the crankshaft in proper position in thechucking devices 48 and 49. These plungers 55 may be recipro catedaxially by means of a pinion 56 formed integral with a suitable shaft 51which engages a rack 58 formed on the plunger 55, the shaft 51 beingprovided with a suitable squared head 59 to which may be applied asuitable wrench for rotating the shaft 51. the plungers 55 into therespective locating holes 36 and 4| the plungers are then locked bymeans of a suitable set screw 69 threaded in the chuck body 48 and 49and bearing against the side of plungers 55 binding them: in the chuckbody when inserted appropriately into the locating holes in the webs ofthe crankshaft.

The conical points as shown in these illustrations may be made of arelatively steep angle or substantially straight if desired so as toprovide adequate driving power on the respective terminal webs l and Iof the shaft without in any way tending to bend the webs or distortthese webs from their true position during the cutting operations of thevarious pin turning tools P on the pin bearings of the crankshaft. Inthis arrangement the previous highly accurate turning of the linebearing portion is relied upon to determine the turning of the pinbearings 6 to 9, inclusive, in accurate relation to the axis of rotationIQ of the crankshaft, the locating plungers serving to accurately indexand drive the crankshaft without twisting the end webs l0 and I5 withrespect to each other, during chucking in the orbital lathe.

Having thus fully set forth and described my invention what I claim asnew and desire to secure by United States Letters Patent is:

1. A method of machining a crankshaft comprising the steps of: (a)drilling center holes in the ends of the crankshaft, (b) mounting saidcrankshaft on centers in said center, holes and machining locating areason the sides of the webs of said crankshaft by machining pressureexerted parallel with the axis of rotation of said crankshaft about saidcenters, (0) and utilizing said locating areas on the sides of the websof said crankshafts for chucking in machining the bearing portions ofsaid crankshaft.

Having thus inserted Y 2. A method of machining crankshafts comprisingthe steps of: (a) drilling center holes in the ends of the crankshafts,(b) mounting said crankshafts by means of centers in said center holesin a drilling machine and drilling center holes in the sides of the websof said crankshaft by feeding pressure exerted parallel with the lineconnecting said centers of said drilling machine, (C) and utilizing saidlocating center holes in the ends of the shaft and in the sides of thewebs for chucking in machining the bearing portions of said crankshafts.

3. A method of machining crankshafts comprising the steps of: (a)drilling center holes in each end of the crankshaft forging or cast- 7ing, (1)) placing said rough forging or casting on centers in saidcenter holes in a drilling machine and drilling center holes in thesides of the webs of said crankshafts, (c) utilizing some of said centerholes for the chucking and turning of the line bearings of saidcrankshafts, (d) and utilizing other of said locating center holes inturning the pin bearings of said crankshafts.

4. A method of machining crankshafts comprising the following steps of:(a) drilling center holes in the ends of the crankshafts, (b)positioning said crankshafts by means of centers in said center holes ina drilling machine and applying center drills to machine locating centerholes in the sides of the faces of the webs of said crankshafts, (c)chucking said crankshafts by means of said center holes in a centerdrive line bearing lathe, (d) and chucking said crankshaft by means ofsaid center holes in an orbital lathe.

5. A method of preparing a crankshaft for chucking in a lathe with arunout of .001" or less comprising the steps of (a) preparing locatingsurfaces on the flange and stub ends of said crankshaft which define theaxis of rotation of said crankshaft; the step (b) of supporting saidcrankshaft by means of said 10- cating surfaces; and the step (c) ofexerting pressure on said crankshaft while so supported, parallel tosaid axis of rotation to form locating surfaces for chucking saidcrankshaft intermediate said first mentioned locating surfaces.

6. A method of preparing a crankshaft for chucking in a lathe with arunout of .001" or less comprising the steps of: (a) preparing locatingsurfaces which define the axis of rotation of said crankshaft; the step(b) of supporting said crankshaft by means. of said 10- pressure on saidcrankshaft, while so supported,

parallel to said axis of rotation to form 10- cating surfaces forchucking said crankshaft intermediate said first mentioned locatingsur-' faces.

7. A method of preparing a crankshaft for chucking in a lathe with arunout of .001" or less comprising the step-s of: (a) preparing locatingsurfaces on the flange and stub ends of said crankshaft which definesthe axis of rotation of said crankshaft; the step (b) of supporting saidcrankshaft by means of said 10- cating surfaces; and the step (c) ofexerting pressure on webs of said crankshaft, while so supported,parallel to said axis of rotation to form locating surfaces for chuckingsaid crankshaft on the axis of rotation of said lathe within said limitsof runout.

WILLARD L. GROENE.

